Recently, the increased demand for sustainable and renewable energy resources have attracted much attention to the development of photovoltaic devices. While silicon-based solar cells require high-cost production processes, dye-sensitized solar cells (DSSC) are promising candidates for photovoltaic applications because of the low cost of raw materials and fabrication. For example, the most efficient polypyridine ruthenium-based DSSCs have achieved power conversion efficiency of more than 11%. However, drawbacks that include environmental concerns limit their applications in DSSC. Other than the ruthenium complexes in DSSC, some dyes may utilize molecules modified with a π-electron push-pull framework (e.g. commercially available porphyrin dyes) to improve charge separation and reduce the intra-molecular charge re-combination. The framework is beneficial for unifying the electron flow direction (such as from donor to acceptor and finally injection into the TiO2 layer) to be applied in solar cells. Although the conventional dyes are not harmful to the environment, they are synthesized by using many steps and a long time, and are purified with difficulty. In short, these dyes cannot be easily prepared by mass-production.